This invention relates in general to radio communication devices, and more specifically to a method and apparatus in such a device for recovering data symbols from a received signal.
Radio communication devices receive selective call messages that have been formatted according to conventional signalling protocols and transmitted as radio signals. Typically, a radio communication device receives the radio frequency (RF) signal, which is mixed down to an intermediate frequency (IF) signal. The IF signal is then processed down to baseband for recovery of data therefrom. However, this method of demodulating the signal to recover data symbols is complex and requires a large amount of circuitry that can consume valuable space within the communication device. Therefore, direct conversion, or zero IF, receivers have been developed for use in communication devices in which space is limited. Direct conversion receivers convert a received RF signal directly to baseband without ever generating an IF signal. Although such direct conversion receivers are generally smaller, conventional demodulation and data recovery techniques are not always suitable for use in direct conversion receivers. Therefore, what is needed is an alternative method of demodulation and data symbol recovery for use with a direct conversion receiver included in a radio communication device.